Self-aligning mandrel



' April 16, 1957 ca. w. DOYLE SELF-ALIGNING MANDREL Filed Jan. 24, 1955 x i g 1 NW Q. H: 5K2 ,M g N i NW NE WW mm v l, r @N N T QN QM @R L W &w .w\

United States PatentC SELF-ALIGNING MANDREL Gilbert W. Doyle, Elkhart, Ind., assignor to Superior Hone Corporation, Elkhart, Ind, a corporation of Indiaua Application January 24, 1955, Serial No. 483,738

8 Claims. (Cl. 51-1843) The present invention relates to mandrels, and particularly, to an improved honing mandrel including means for automatically aligning or centering the mandrel in a bore to be honed.

It is a specific object of the invention to provide an improved honing mandrel including means for centering the mandrel on one end of a bore to accommodate accurate honing of the other end of the bore coaxially of the said one end of the bore.

By way of example of the application of the present invention, it is observed that in die sets having press fitted tubular bushings in one die piece for slidably mounting and aligning the leader pins on the other die piece, it is essential that the bushings be accurately formed intimately to receive the leader pins without binding. The bushings are originally formed accurately, but as the same are press fitted into one die piece, there is a tendency for the inner end of each bushing to be squeezed inwardly with a resultant decrease in the inner diameter of the inner end of the, bushing. Accordingly, the inside of the bushing becomes slightly tapered and it is necessary to hone the inner end portion of the bore of the bushing to the same diameter as the outer end portion of the bore. As will be appreciated, the bore must be true or straight after honing to receive the leader pins accurately and without binding.

It is an object of the invention to provide an improved honing mandrel especially adapted for honing operations of the above and like character, including movable wear plate means engageable in and automatically centering on the outer end of a bore to center the honing stone means of the mandrel in the inner end portion of the bore.

A further object of the invention, is the provision of an improved self-aligning or self-centering honing mandrel of the character defined including a rotatable head and shaft member, a plurality of honing stones movably mounted on the head and shaft member to be biased radially outward into engagement with the wall of the bore to be honed, and three or more circumferentially spaced and resiliently biased wear plates carried by the head and shaft member and including portions spaced longitudinally from the honing stones to be biased outwardly into engagement with the wall of the bore to center the head and shaft member and the honing stones in the bore.

A still further object of the invention is the provision of an improved self-aligning honing mandrel that is highly practical, sturdy and economical.

Other objects and advantages of the present invention will become apparent in the following detailed description of a preferred embodiment of the invention.

Now, in order to acquaint those skilled: in the art with the manner of making and using the self-aligning mandrel of the invention, I shall describe, in connection with the accompanying drawings, a preferred, embodiment of the invention. i

2,788,621 Patented Apr. 16, 1957 In the drawings:

Figure 1 is a longitudinal sectional view of a preferred embodiment of the mandrel of the invention, the view showing the mandrel applied to a driver and entering into a work piece;

Figure 2 is a cross-sectional view of the mandrel taken substantially on line 2-2 of Figure l; and

Figure 3 is a cross-sectional view of the mandrel taken substantially on line 33 of Figure 1.

Referring to the drawings, the mandrel of the invention is indicated generally at 10, the same: being adapted to be rotated by a driver 12 to hone, by way of example, the bore of a tubular bushing 14 which is press fitted into a die or like work piece 16. The bushing, as shown, includes an enlarged head and a shank portion which is pressed into the die piece 16. As the shank of the bushing is pressed into the bore in the die piece, the inner end thereof is squeezed radially inwardly so that the diameter of the bushing bore is decreased at the inner end thereof, as is indicated in exaggerated fashion at 18 in Figure 1, while the bushing bore diameter in the region of the head remains unchanged. As is ob vious, the purpose of the honing operation to be performed is to render the bushing bore true and of uniform diameter throughout.

The mandrel 10 preferably comprises an integral head and shaft member 20 including a shaft portion 22 to be slidably received in the driver 12 and a head portion 24 projecting forwardly of the driver. The head portion 24 of the member 24 is generally cylindrical and is provided with a plurality of circumferentially spaced, radially open slots of two classes, the two classes of slots preferably being of the same number and arranged alternately. The first class of slots comprises stone receiving slots 26 which each include a relatively deep and narrow radial slot portion extending longitudinally through the head 24 and into the shaft 22 and a relatively wide outer portion or recess 28 which is of progressively decreasing depth from the outer toward the inner end of the head 24 to define a tapered or inclined base wall 36. Each of the slots 26 and recesses 28 is adapted for the reception of a stone assembly including a honing stone 32 mounted on a shoe 34' which in turn is mounted on an elongate, narrow retainer or retainer spring 36. Each stone 32 is mounted in a recess 28 and has a base wall complemental to the base wall 30 of the recess, so that upon relative longitudinal movement of the stones 32 and the member 20, the stones are moved radially with respect to the member 20. To retain the stones 32 in the recesses 28 each recess is provided with at least one laterally extending kerf paralleling the wall 30 within which an overhanging edge portion 38 of the respective shoe 34 is slidably received. The spring 36 of each stone assembly extends longitudinally rearward within the respective slot 26 to the driver 12, the rearward end of the spring being turned radially outward to be secured to the driver, which comprises a tubular spindle, by means of a spindle end cap 40. The shaft 22 of the member 29 is associated with a longitudinally movable control member (not shown) which is rotated conjointly with the driver 12, whereby the driver 12 and the mandrel 10 are rotated as a unit. Upon suitable actuation of the control member, during rotation of the mandrel 10 and driver 12, the member 2% is moved forwardly (to the right as shown) with respect to the driver 12. As this movement of the member 24) occurs, the stones are held against longitudinal movement by the driver 12 and the cap 40, whereby the stones 32 are biased radially outward due to their engagement with the forwardly moving inclined surfaces 30. To retain the stones against longitudinal 'disassembly'should' one of the springs 36 break, or the like, a nose piece or end cap 42 overlying the ends of the slots 26 is secured to the forward end of the head 24, by a countersunk screw or the like.

To the extent presently described, the mandrel is generally the same as described and claimed in Patent No. 2,419,136, to Albert P. Hasty, issued April 15, 1947, and it is the object of the present invention to improve upon this mandrel by rendering the same self-aligning. Specifically, according to the invention, the mandrel head 24 is provided with a second class of slots 44, as previously referred to, which each comprise a relatively narrow, relatively shallow, longitudinally extending slot of uniform depth provided adjacent the rearward end thereof with a radial depression or recess and at the forward end thereof with aligned kerfs in the opposite walls thereof opening to the forward end of the head 24. Each slot 44 is adapted for the reception of a wear strip or plate 46 comprising a relatively thin strip of metal provided with a laterally extending pin 48 at its forward end and an offset or reduced extension St) at its rearward end. Each wear strip 46 is inserted in a slot 44 by sliding of the pin 48 into the kerfs at the forward end of the slot pivotally to mount the strip in the slot. As is to be appreciated, the nose piece 42, when attached to the head 24, retains the wear strips, as well as the stone assemblies, in their respective slots. Adjacent its rearward end, in alignment with the radial depression in the respective slot 44, each wear strip is provided with a corresponding depression or recess and a compression spring 52 is fitted into the aligned recesses normally to bias the rearward end of each wear strip radially outwardly about the pivotal mounting thereof at 48. To retain the rearward end of the Wear strip against disassociation from the head 24, a retaining ring 54 is fitted over the rearward end of the head 24 and over the extensions 50 of the wear strips, the said extensions, as noted, being reduced or offset to accommodate relative movement of the strips with respect to the head and the ring. The ring may suitably be secured to the head 24 by a set screw 56 engaging the cylindrical surface of the head between adjacent slots 26 and 44.

To perform an accurate centering function, it is necessary that at least three wear strips be provided at circumferential spacings of approximately 120", as is shown in Figures 2 and 3. In such instance, it is desirable to employ three stone assemblies centered between adjacent wear strips. However, more or less honing stone assemblies may be employed, and in any given construction more than three wear strips may be provided. Preferably, however, in any case, the wear strips and the honing stone assemblies are of the same number, and are alternately arranged about the head 24 at equal circumferential spacings, as shown in the preferred embodiment disclosed herein.

In use, the mandrel 10 and driver 12 are moved toward the work piece to enter the nose piece 42 and the forward end of the mandrel into the bore of the bushing. As this movement occurs, as is shown in Figure 1, the wear strips 46, which are normally biased outwardly by the springs 52, engage in the outer undistorted portion of the bushing bore and automatically center the mandrel with respect to the bushing. The mandrel is then rotated and inward movement thereof is continued to move the stones to the distorted inner end portion of the bore, whereupon the shaft and head member 20 is moved forwardly with respect to the stones to bias the stones uniformly into engagement with the distorted wall portion 18 of the bore. During honing, the mandrel is prefera-bly reciprocated to effect an optimum honing action. During all of these movements, the wear strips center the mandrel in the bore, and the springs 52 yield and expand as may be necessary to maintain the wear strips in centering engagement with the outer end of the bushing bore, whereby the bore may be honed to be perfectly true and of uniform diameter throughout.

From the foregoing, it is to be appreciated that the present invention provides an improved honing mandrel that is self-aligning and automatically centers itself in the outer end of a bore having an inner portion to be honed. At the same time, the mandrel is of a simplified and sturdy construction and is economical of manufacture and assembly. Application of the principles herein disclosed to tools and mandrels of a character similar to honing mandrels will be apparent to those skilled in the art. Also, application of the principles herein disclosed to stepped bores is apparent.

While I have shown and described what I regard to be a preferred embodiment of my invention, it will be appreciated that various changes, rearrangements and modifications may be made therein without departing from the scope of the invention, as defined by the appended claims.

I claim:

1. A honing mandrel comprising a rotatable member having a plurality of relatively deep narrow slots extending longitudinally therethrough at substantially equal circumferential spacings, a recess having an inclined base wall communicating with each of said slots adjacent one end of said member, a honing stone slidably mounted in each of said recesses and including a retainer extending through the respective slot toward the other end of said member, a second set of relatively shallow slots extending longitudinally through said member, the slots of said second set being at least three in number and located at substantially equal circumferential spacings, a wear strip pivotally mounted at one end thereof in each of the slots of said second set adjacent said one end of said member, a spring disposed between said member and each of said strips adjacent said other end of said member, and a retainer encircling said strips and said member adjacent said other end thereof.

2. A honing mandrel comprising a rotatable member having at least three relatively deep narrow slots extending longitudinally therethrough at substantially equal circumferential spacings, a recess having an inclined base wall communicating with each of said slots adjacent one end of said member, a honing stone slidably mounted in each of said recesses and including a retainer extending through the respective slot toward the other end of said member, a second set of relatively shallow slots of the same number as the first set of slots extending longitudinally through said member, the slots of said second set being located at substantially equal circumferential spacings intermediate said relatively deep slots, a wear strip pivotally mounted at one end thereof in each of the slots of said second set adjacent said one end of said member, a spring disposed between said member and each of said strips adjacent said other end of said member, a ring encircling said retainers, said strips and said member adjacent said other end thereof to retain said strips against radial disassociation, and a nose piece secured to said one end of said member to retain said strips against longitudinal disassociation.

3. A self-aligning mandrel comprising a supporting member, said supporting member having at least three longitudinally extending outwardly open slots therein at substantially equal circumferential spacings, said slots each being open at one end of said supporting member and having kerfs in the opposite walls thereof adjacent to and open at said one end of said supporting member, a plate mounted in each of said slots, said plates each having a transverse pin adjacent one end thereof slidably received in the kerfs in the respective slot pivotally to mount said plates in said slots adjacent said one end of said supporting member, an end piece secured to said one end of said supporting member and closing the open ends of said slots and kerfs to prevent disassociation of said plates from said supporting member, means between said supporting member and said plates adjacent the opposite ends of said plates normally biasing said opposite ends-of said plates outwardly of said supporting member, and means adjacent said opposite ends of said plates limiting outward movement of said opposite ends of said plates.

4. A self-aligning mandrel as set forth in claim 3, said plates being received throughout their lengths in said slots, said supporting member having an outwardly open recess in the bottom wall of each of said slots adjacent said opposite ends of said plates, said plates each having an inwardly open recess therein aligned with the recess in the respective slot, the said biasing means comprising a compression spring in each of said slots received at its opposite ends in the recesses in the respective slot and plate.

5. A self-aligning mandrel for performing work on the wall of a bore in a work piece, comprising an elongate supporting member, a work performing member mounted on said supporting member adjacent one end thereof for lateral movement with respect to said supporting member, said supporting member having at least three longitudinally extending outwardly open slots therein at equal circumferential spacings, an elongate aligning plate mounted in each of said slots, said plates each being pivotally mounted adjacent one end thereof in the respective slot adjacent said one end of said supporting member, and spring means between said supporting member and each of said plates adjacent the opposite ends of said plates to bias the said opposite end portions of said plates outwardly of said supporting member, said plates upon insertion of said one end of said supporting member into the bore of the work piece engaging the work piece at the outer end of the bore in spaced relation to said work performing member to align said work performing member within the interior of the bore.

6. A self-aligning honing mandrel for honing the wall of a bore in a work piece, comprising an elongate rotatable member having two sets of circumferentially spaced 1ongitudinally extending radially open slots therein, a honing stone assembly mounted for longitudinal and radial movement in each slot of one of said sets of slots adjacent one end of said member, means for moving said stones to engage the same with and to disengage the same from the wall of the bore, an elongate aligning plate mounted in each slot of the other of said sets of slots, the slots of said other set being at least three in number and disposed at equal circumferential spacings, said aligning plates each being pivotally mounted at one end thereof adjacent said one end of said member in the respective slot, extending toward the other end of said member and terminating in longitudinally spaced relation to said stones, and a spring in each of said slots of said other set confined between said member and the respective aligning plate adjacent the terminal end of said plate to bias the terminal end portion of each plate radially outwardly of said member, said plates upon insertion of said one end of said member into the bore of the work piece engaging the work piece at the outer end of the bore in spaced relation to said stones to align said member and said stones within the interior of the bore.

7. A self-aligning honing mandrel as set forth in claim 6, said stones and said member having cooperating cam surfaces effective upon relative longitudinal reciprocation of said stones and said member to move said stones radially of said member, said means for moving said stones including a driver rotatable with said member and relatively movable longitudinally of said member, said stones having fixed connection to said driver, said aligning plates being secured to said member against relative longitudinal movement at the said pivotal mountings thereof.

8. A self-aligning honing 1 ndrel as set forth in claim 6, said slots each being ope; at said one end of said member, said slots of said Olilral' set each having kerfs in the opposite walls thereof adjacent to and open at said one end of said member, said aligning plates each having a transverse pin therein adjacent said one end thereof slidably received in the kerfs in the respective slot pivotally to mount the plate in the slot adjacent said one end of said member, said slots of said one set: each having a longitudinally extending radially inclined kerf in at least one side wall thereof adjacent to and open at said one end of said member, said stone assemblies each including a shoe slidably received in the kerf in the respective slot movably to mount the stone in the slot adjacent said one end of said member, and a nose piece secured to said one end of said member and closing the open ends of said slots and kerfs to prevent inadvertent disassociation of said plates and stone assemblies from said member.

References Cited in the file of this patent UNITED STATES PATENTS 1,030,634 Adamson June 25, 1912 1,484,353 Kidwell Feb. 19, 1924 2,051,569 Morrison Aug. 18, 1936 2,252,809 Kline Aug. 19, 1941 2,304,930 Klein Dec. 15, 1942 2,419,136 Hasty Apr. 15, 1947 2,581,601 Peden a. Jan. 8, 1952 2,657,506 Hadley Nov. 3, 1953 

